The objective of this research is the definition of a relationship of bile acids or their derivatives to the etiology of cancer of the large bowel. Specifically, we propose to ascertain dietary effects on the nature and amounts of bile acids found in hepatobiliary circulation and in the lumen of the colon. Gas liquid chromatography, thin layer chromatography, radioassay, and mass spectrometry will be used to identify and quantitate fecal sterols and bile acids. High-pressure liquid chromatography will be employed to separate, identify and measure the quantities of conjugated bile acids in the enterohepatic circulation.